Rate Indication and Link Adaptation for Variable Data Rates in Long Range Wireless Networks

ABSTRACT

A method of fast link adaptation for Bluetooth long-range wireless networks is provided. A data packet comprises a preamble, a first packet portion including a rate indication field, and a second packet portion including a PDU. The first packet portion is encoded using a first modulation and coding scheme with a first rate while the second packet portion is encoded using a second modulation and coding scheme with a second rate indicated by the RI field. A transmitter thus can use different MCS options to support variable data rates by adapting to channel conditions, and then uses the novel RI field to indicate the data rate to a receiver dynamically. As a result, fast link adaptation can be achieved for different applications with different rate requirements, to provide higher data rate, reduce connection time, lower power consumption, and improve link quality.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of, and claims priority under35 U.S.C. §120 from nonprovisional U.S. patent application Ser. No.14/848,108, entitled “RATE INDICATION AND LINK ADAPTATION FOR LONG RANGEWIRELESS NETWORKS,” filed on Sep. 8, 2015, the subject matter of whichis incorporated herein by reference. Application Ser. No. 14/848,108, inturn, claims priority under 35 U.S.C. §119 from U.S. ProvisionalApplication No. 62/047,706, entitled “Link Adaptation for Long Range,”filed on Sep. 9, 2014; U.S. Provisional Application No. 62/052,519,entitled “Rate Indication and Link Adaptation for Long Range,” filed onSep. 19, 2014, the subject matter of which is incorporated herein byreference. This application also claims priority under 35 U.S.C. §119from U.S. Provisional Application No. 62/060,095, entitled “Long RangeData Rates,” filed on Oct. 6, 2014, the subject matter of which isincorporated herein by reference.

TECHNICAL FIELD

The disclosed embodiments relate generally to wireless networkcommunications, and, more particularly, to rate indication and linkadaptation for Low energy (LE) long range Bluetooth wireless networks.

BACKGROUND

Bluetooth is a wireless technology standard for exchanging data overshort distances (using short-wavelength UHF radio waves in the ISM band)from fixed and mobile devices and building personal area networks(PANS). Bluetooth operates at frequencies between 2400 and 2483.5 MHz(including guard bands 2 MHz wide at the bottom end and 3.5 MHz wide atthe top). This is in the globally unlicensed Industrial, Scientific andMedical (ISM) 2.4 GHz short-range radio frequency band. Bluetooth uses aradio technology called frequency-hopping spread spectrum. Bluetoothdivides transmitted data into packets, and transmits each packet on oneof 79 designated Bluetooth channels. Each channel has a bandwidth of oneMHz. Bluetooth 4.0 uses 2 MHz spacing, which accommodates 40 channels.The first channel starts at 2402 MHz and continues up to 2480 MHz in 2MHz steps. It usually performs 1600 hops per second, with AdaptiveFrequency-Hopping (AFH) enabled.

Bluetooth low energy (Bluetooth LE, BLE) is a wireless personal areanetwork technology designed and marked by the Bluetooth Special InterestGroup aimed at novel applications in the healthcare, fitness, beacons,security, and home entertainment industries. Compared to Bluetooth, BLEis intended to provide considerably reduced power consumption and costwhile maintaining a similar communication range. BLE uses frequencyhopping to counteract narrowband interference problems. The LE systememploys a frequency hopping transceiver to combat interference andfading and provides many frequency hopping spread spectrum (FHSS)carriers. FHSS is a method of transmitting radio signals by rapidlyswitching a carrier among many frequency channels.

The majority of channel signal to noise ratios (SNRs) vary within +/−5dB. Without fast rate adaptation, the radio needs to operate at thelowest data rate or high SNR to maintain the PER. More than two datarates might be required for 10 dB SNR variations. In Bluetooth/BLE,Channel Quality Driven Data Rate Change (CQDDR) is a channel ratecontrol algorithm implemented in Link management protocol (LMP) for rateadaptation. The signaling exchange of LMP messages relies on theunderlying physical layer link, which might not work well in poorsignal-to-noise ratio condition.

While short-range Bluetooth/BLE communication is between individualradios within a distance of 5 to 10 meters, long-range Bluetooth/BLEcalls for a distance of about 100 meters or longer. The long-rangechannel characteristics is considerably different from the short-rangechannel characteristics. Long-range channels have lower operating SNR,frequency selective fading, and has faster time domain variations alongthe propagation path. The hopping channels may have significantlydifferent SNRs because it is difficult to find hopping sequence/channelmap satisfying all nodes within a Piconet. Longer packet length is alsomore susceptible to mid-packet collisions and requires trickier linkmanagement operation. If the link management is not robust, thenlong-range communication also results in higher power consumption due tore-transmission.

The existing LMP/CQDDR is a MAC layer protocol. The TX and RX radios usethe PHY layer PDU to transmit LMP messages and need to establishhandshake. Overall, LMP is a very slow adaptation process: the receiverMAC layer operation detects channel degradation usually after multiplepackets, and then requests a preferred rate to the transmitter. If thephysical link is nearly lost, or the ACK is not properly received, theradio can make a few retries until the LMP message is successfullyacknowledged and the transmitter can switch to preferred rate afternegotiation. If link is lost, both sides rely on timeout to trydifferent PHY rates. In some cases, the PHY layer link might be brokenand LMP messages cannot be reliably exchanged. Another drawback is thattransmitter cannot unilaterally switch PHY data rate without messageexchange with the receiver or after time-out. As a result, the existingLMP/CQDDR is difficult to adapt properly with varying SNRs at differentchannels, especially for long range Bluetooth or BLE communication.Further, the transmitter that purely relies on LMP message for linkadaptation would not easily attempt high data rate since, if link is notreliably at higher rate, it would take a long time to recover.

A solution is sought to improve rate adaptation for long-rangeBluetooth/BLE communication.

SUMMARY

A method of fast link adaptation for Bluetooth long-range wirelessnetworks is provided. A novel rate indication (RI) field is incorporatedin a data packet to enable auto detection of rate adaptation at thereceiver side. The data packet comprises a preamble, a first packetportion including the RI field, and a second packet portion includingthe PDU. The first packet portion is encoded with a first rate while thesecond packet portion is encoded with a second rate indicated by the RIfield. In a preferred embodiment, the first packet portion is encodedwith an error correction code that terminates within the first portion.The second packet portion may or may not encoded with an errorcorrection code.

In accordance with a novel aspect, the transmitting device raise/lowerthe encoding rate when the link quality is good/poor. The receivingdevice can provide recommended rate or link quality feedback informationvia a link management protocol (LMP) message to help the transmittingdevice making the rate adaptation decision. The transmitting device canalso unilaterally decide the data rate for the second packet portionwithout the receiver recommendation. This is especially important if thelink condition is poor and the transmitting device can attempt a lowerdata rate without waiting for a time-out. Additionally, the transmittingdevice can also start with a high data rate to speed up the datatransfer and to save power consumption.

In one embodiment, a transmitting device indicates and adapts a datarate associated with a data packet to be transmitted to a receivingdevice in a wireless communication network. The data packet comprises apreamble, a first packet portion, and a second packet portion. Thetransmitting device encodes the first packet portion in accordance witha first rate. The first packet portion comprises a rate indicationfield. The transmitting device encodes the second packet portion inaccordance with a second rate. The second rate is indicated based on avalue of the rate indication field. In a preferred embodiment, the firstpacket portion is encoded with an error correction code that terminatewithin the first portion. The second packet portion may or may not beencoded with an error correction code. Finally, the transmitting devicetransmits the data packet to the receiving device in the wirelesscommunication network. In one example, the transmitting device raisesthe second rate when detecting the link quality is good or in an attemptto speed up data transfer or conserve power. In another example, thetransmitting device lowers the second rate when detecting the linkquality is poor.

In another embodiment, a receiving device receives a data packet from atransmitting device in a wireless communication network. The data packetcomprises a preamble, a first packet portion, and a second packetportion. In a preferred embodiment, the first packet portion is encodedwith an error correction code that terminate within the first portion.The second packet portion may or may not be encoded with an errorcorrection code. The receiving device decodes the first packet portionin accordance with a first rate. The first packet portion comprises arate indication field. The receiving device decodes the second packetportion in accordance with a second rate. The second rate is indicatedbased on a value of the rate indication field. In one example, thereceiving device provides feedback information to the transmittingdevice via an LMP message. In another example, the receiving deviceprovides recommended information to the transmitting device via a rateindication field for fast feedback. The recommended informationcomprises a recommended rate or a transmit power adjustment.

In accordance with another novel aspect, a transmitter uses differentmodulation and coding scheme (MCS) options to support variable datarates by adapting to channel conditions, and then uses the novel RIfield to indicate the data rate to a receiver dynamically. As a result,for Bluetooth Long Range with varying SNRs, fast link adaptation can beachieved for different applications with different rate requirements, toprovide higher data rate, reduce connection time, lower powerconsumption, and improve link quality.

In one embodiment, a wireless transmitting device indicates and adapts adata rate associated with a data packet to a receiving device in aBluetooth Long Range wireless network. The data packet comprises apreamble, a first packet portion, and a second packet portion. Thetransmitting device encodes the first packet portion using a firstmodulation and coding scheme (MCS) in accordance with a first data rate.The first packet portion comprises a rate indication field. Thetransmitting device encodes the second packet portion using modulationand coding scheme in accordance with a second data rate based on a valueof the rate indication field. The transmitting device transmits the datapacket to the receiving device in the wireless network. In one example,the first data rate is 125 Kbps with convolutional forward errorcorrection and one to four pattern mapping, and the second data rate is500 Kbps with convolutional forward error correction and no patternmapping.

In another embodiment, a wireless receiving device receives a datapacket transmitted from a transmitting device in a Bluetooth Long Rangewireless network. The data packet comprises a preamble, a first packetportion, and a second packet portion. The receiving device decodes thefirst packet portion in accordance with a first modulation and codingscheme corresponding to a first data rate. The first packet portioncomprises a rate indication field. The receiving device decodes thesecond packet portion in accordance with a second modulation and codingscheme corresponding to a second data rate based on a value of the rateindication field. In one example, the first data rate is 125 Kbps withconvolutional forward error correction and one to four pattern mapping,and the second data rate is 500 Kbps with convolutional forward errorcorrection and no pattern mapping.

Other embodiments and advantages are described in the detaileddescription below. This summary does not purport to define theinvention. The invention is defined by the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication network and a data packetwith a rate indication field in accordance with one novel aspect.

FIG. 2 is a simplified block diagram of a wireless transmitting deviceand a receiving device in accordance with a novel aspect.

FIG. 3 illustrates one embodiment of rate indication for fast linkadaptation in a Bluetooth long-range wireless network.

FIG. 4 illustrates another embodiment of rate indication for fast linkadaptation in a Bluetooth long-range wireless network.

FIG. 5 illustrates one embodiment of fast link adaptation withrecommendation or feedback from the receiving device.

FIG. 6 illustrates FEC encoding and an example of the rate indication(RI) field of a data packet in accordance with one novel aspect.

FIG. 7 is flow chart of a method of rate indication from transmitterperspective in accordance with a novel aspect.

FIG. 8 is a flow chart of a method of rate indication from receiverperspective in accordance with a novel aspect.

FIG. 9 illustrates different MCS options for Bluetooth long range.

FIG. 10 is a simplified block diagram for supporting variable data ratesfor Bluetooth long range.

FIG. 11 is a flow chart of a method of supporting variable data ratesfrom transmitter perspective in accordance with one novel aspect.

FIG. 12 is a flow chart of a method of supporting variable data ratesfrom receiver perspective in accordance with one novel aspect.

DETAILED DESCRIPTION

Reference will now be made in detail to some embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings.

FIG. 1 illustrates a wireless communications network 100 and a datapacket 110 with a rate indication (RI) field 120 in accordance with onenovel aspect. Wireless communication network 100 comprises a wirelesstransmitting device 101 and a wireless receiving device 102. Wirelesscommunication network 100 is a Bluetooth low energy (Bluetooth LE, BLE)network. Bluetooth LE applies a wireless personal area networktechnology designed and marked by the Bluetooth Special Interest Group.Compared to Bluetooth, BLE is intended to provide considerably reducedpower consumption and cost while maintaining a similar communicationrange. BLE uses frequency hopping to counteract narrowband interferenceproblems. The BLE system employs a frequency hopping transceiver tocombat interference and fading and provides many frequency hoppingspread spectrum (FHSS) carriers. FHSS is a method of transmitting radiosignals by rapidly switching a carrier among many frequency channels.

In the example of FIG. 1, the distance between transmitting device 101and receiving device 102 may be longer than 100 meters, resulting in along-range BLE communication channel. The long-range BLE channelcharacteristics is considerably different from the short-range channelcharacteristics. Long-range channels have lower operating signal tonoise ratio (SNR), frequency selective fading, and has faster timedomain variations along the propagation path. The hopping channels mayhave significantly different SNRs because it is difficult to findhopping sequence/channel map satisfying all nodes within a Piconet.Longer packet length is also more susceptible to mid-packet collisionsand requires trickier link management operation. If the link managementprotocol is not robust, then long-range communication also results inhigher power consumption.

In principle, rate adaptation increases network throughput and reducespower consumption by reducing re-transmissions and reducing airtime. InBluetooth/BLE, Channel Quality Driven Data Rate Change (CQDDR) is achannel rate control algorithm implemented in Link management protocol(LMP) for channel-to-channel rate adaptation. However, the existingLMP/CQDDR does not provide fast rate adaptation. It is a MAC layerprotocol. The TX and RX radios use the same PHY rate to transmit LMPmessages and need to establish handshake. Overall, LMP is a very slowadaptation process: the receiver detects channel degradation, receiverrequests a preferred rate, and the transmitter switches to preferredrate after negotiation. MAC layer needs multiple packets to go througheach of above step. In some cases, the PHY layer link might be nearlybroken and LMP messages cannot be reliably exchanged. If the link islost, both sides rely on timeout to try different PHY rates. As aresult, the existing LMP/CQDDR is difficult to adapt properly withvarying SNRs at different channels, especially for long range Bluetoothor BLE communication.

In accordance with one novel aspect, a novel rate indication (RI) fieldis incorporated in the data packet to enable auto detection of fast linkadaptation at the receiver side. In wireless communications network 100,the wireless devices communicate with each other through variouswell-defined packet preamble structures. For example, the transmittingdevice 101 encodes and transmits a data packet 110. The receiving device102 receives data packet 110 and tries to decode data packet 110. Datapacket 110 comprises preamble, an access address field, a rateindication (RI) field 120, a first TERM1 field, a payload data Unit(PDU), CRC, and a second TERM2 field. The first three fields (accessaddress, RI, and TERM1) form a first FEC block 1, while the next threefields (PDU, CRC, and TERM2) form a second FEC block 2. In one preferredembodiment, the second FEC block 2 might not be encoded with FEC.

The preamble is not coded and therefore transmitted and received at LE1M. The preamble is 10 octets (80 bits) in length and consists of 10repetitions of the 00111100b bit pattern. The FEC block 1 consists ofthree fields: the Access Address, RI, and TERM1. The Access Address is32 bits. The RI field consists of two bits. In one example, a RI bitpattern of 00b indicates that the FEC Block 2 is coded at LE 125 k, anda RI bit pattern of 01b indicates that the FEC Block 2 is coded at LE500 k. Note that the 2 bits in RI field can have four possible bitpatterns. Only, two of the four possible bit patterns are used now. Theremaining 2-bit patterns are for reserved for future use. TERM1 is 3bits in length with the value of each bit set to zero. FEC block 1 iscoded in accordance with a fixed rate, e.g., at 125 k. The FEC block 2consists of three fields: the PDU, CRC, and TERM2. CRC is 24 bits inlength and the value is calculated over all PDU bits. TERM2 is 3 bits inlength with the value of each bit set to zero. FEC block 2 is coded inaccordance with the rate indicated by the RI field. For example, ifRI=00b, then the FEC block 2 is coded ate LE 125 k. If RI=01b, then theFEC block 2 is coded at LE 500 k. Since the RI field indicates thecoding rate, it is also referred to as a “coding indicator (CI)”.

With the RI field, fast rate adaption can be achieved for long-rangeBLE. No handshaking or synchronization is required for data rate change.The transmitter can change the data rate on each individual channelunilaterally. Fast adaptation is feasible because the transmitter canmake the decision directly based on channel quality, whether ACK isreceived or not, receiver status, or receiver recommendation, etc.Transmitter can simply use a trial and error approach. For example,transmitter can start with a high data rate to save power and speed upthe data transfer and if no ACK, it immediately switches to low rate.

FIG. 2 is a simplified block diagram of wireless devices 201 and 211 inaccordance with a novel aspect. For wireless device 201, antenna 207transmits and receives radio signals. RF transceiver module 206, coupledwith the antenna, receives RF signals from the antenna, converts them tobaseband signals and sends them to processor 203. RF transceiver 206also converts received baseband signals from the processor, convertsthem to RF signals, and sends out to antenna 207. Processor 203processes the received baseband signals and invokes different functionalmodules to perform features in wireless device 201. Memory 202 storesprogram instructions and data 208 to control the operations of thewireless device.

Similar configuration exists in wireless device 211 where antenna 217transmits and receives RF signals. RF transceiver module 216, coupledwith the antenna, receives RF signals from the antenna, converts them tobaseband signals and sends them to processor 213. The RF transceiver 216also converts received baseband signals from the processor, convertsthem to RF signals, and sends out to antenna 217. Processor 213processes the received baseband signals and invokes different functionalmodules to perform features in wireless device 211. Memory 212 storesprogram instructions and data 218 to control the operations of thewireless device.

The wireless devices 201 and 211 also include several functional modulesto carry out some embodiments of the present invention. The differentfunctional modules are circuits can be configured and implemented bysoftware, firmware, hardware, or any combination thereof. The functionmodules, when executed by the processors 203 and 213 (e.g., viaexecuting program codes 208 and 218), for example, allow device 201 toencode and transmit a bit stream to device 211, and allow device 211 toreceive and decode the bit stream accordingly. Link adaptation module209/219 comprises encoder 205/215, decoder 204/214, and rate indicationcircuit 208 and/or rate feedback circuit 218. In one example, at thetransmitter side, rate indication circuit 208 determines an adaptivesymbol rate of a packet to be transmitted, encoder 205 inserts the RIfield into a bit stream of the data packet and performs FEC encoding onthe PDU of the data packet based on the symbol rate indicated by the RIfield. At the receiver side, the decoder 215 examines the RI field anddecodes the PDU of the data packet based on a symbol rate indicated bythe RI field accordingly. The rate feedback circuit 218 may alsorecommend a preferred symbol rate of the receiver to the transmitter, orprovide link quality feedback information to the transmitter.

FIG. 3 illustrates one embodiment of rate indication for fast linkadaptation in a Bluetooth long-range wireless network. In step 311,transmitter 301 and receiver 302 establish a connection for exchangingdata packets. For power saving, the connection interval is in the orderof hundreds of milliseconds. As a result, the same chancel is used forthe same connection event and multiple packets are exchanged in the samechannel. In the example of FIG. 3, in step 312, the transmitter and thereceiver exchanges data packets at a high symbol rate, e.g., 500 k.However, the transmitter detects that the link quality is not good. Forexample, the transmitter receives NACK or does not receive ACK from thereceiver. In step 313, the transmitter decides to switch to a lowersymbol rate, e.g., 125 k for the next data packet. In step 314, thetransmitter transmits a data packet with an RI field. The packetcomprises a first FEC block and a second FEC block. The first FEC blockcomprises the RI field, while the second FEC block comprises the PDU.The RI field indicates that the second FEC block is encoded with a lowersymbol rate of 125 k. In step 315, the receiver retrieves the RI fieldfrom the data packet and decodes the PDU based on the indicated symbolrate of 125 k.

FIG. 4 illustrates another embodiment of rate indication for fast linkadaptation in a Bluetooth long-range wireless network. In step 411,transmitter 401 and receiver 402 establish a connection for exchangingdata packets. For power saving, the connection interval is in the orderof hundreds of milliseconds. As a result, the same chancel is used forthe same connection event and multiple packets are exchanged in the samechannel. In the example of FIG. 4, in step 412, the transmitter and thereceiver exchanges data packets at a low symbol rate, e.g., 125 k.However, the transmitter detects that the link quality is good. Forexample, the transmitter successfully receives ACK from the receiver andthe SNR is above a threshold. In step 413, the transmitter decides toswitch to a higher symbol rate, e.g., 500 k for the next data packet. Instep 414, the transmitter transmits a data packet with an RI field. Thepacket comprises a first FEC block and a second FEC block. The first FECblock comprises the RI field, while the second FEC block comprises thePDU. The RI field indicates that the second FEC block is encoded with ahigher symbol rate of 500 k. In step 415, the receiver retrieves the RIfield from the data packet and decodes the PDU based on the indicatedsymbol rate of 500 k.

FIG. 5 illustrates one embodiment of fast link adaptation withrecommendation or feedback from the receiving device. In step 511,transmitter 501 and receiver 502 establish a connection and exchangedata packets encoded with a previous rate. In step 512, the receiversends an LMP (link management protocol) message to the transmitter withfeedback information. For example, the receiver may provide arecommended data rate to the transmitter based on the receiver's ownpreference and the link quality. In another example, the receiverprovides recommended information via the RI field for fast feedback. Therecommended information comprises either a recommended data rate or arecommended TX power adjustment. The transmitter makes the finaldecision based on the feedback information. The present invention thusprovides a novel way to combine the MAC layer LMP and the PHY layer RIin a coherent way. The two protocols work in harmony—e.g., any conflictbetween the MAC layer recommendation and the PHY layer RI is determinedsince the priority is given to the transmitter setting of the RI.

In step 513, the transmitter receives the LMP message and decideswhether to adopt the recommended data rate or not. Note that thetransmitter is the final decision maker here. There is no handshaking ornegotiation involved. The receiver merely provides a recommendation. Thetransmitter makes the final decision of a new encoding rate for the nextPDU and indicates the new encoding rate via the RI field. In step 514,the transmitter encodes the PDU of the data packet in accordance withthe new rate and indicates the new rate via the RI field. In step 515,the receiver retrieves the RI field from the data packet and decodes thePDU of the data packet based on the new rate.

FIG. 6 illustrates FEC encoding and examples of the rate indication (RI)field of a data packet in accordance with one novel aspect. Asillustrated in FIG. 6, data packet 610 (except for the preamble part) isfirst coded by the convolutional forward error correction (FEC) encoder601, and then spread by the inner pattern mapper 602 beforetransmission. At the receiver side, the received bit stream is de-mappedby pattern de-mapper 612, and then decoded by FEC decoder 611. Note thatthe RI field in FEC block 1 is also convolutional FEC encoded, with afixed low rate of 125 k. Therefore, RI is protected even at lower SNR.On the other hand, the PDU in FEC block 2 is FEC encoded with anadaptive rate indicated by RI. The transmitter is able to quickly decidean appropriate rate that is adaptive to the link quality. As a result,network throughput is improved.

FIG. 6 also illustrates an example of the RI field. In the exampledepicted by table 631, RI has two bits. RI=x0b indicates a data rate of125 kbps (coded), RI=x1b indicates a data rate of 500 kbps (un-coded),where the MSB bit is reserved for future use. Since RI indicates thecoding rate, it is also referred to as a “coding indicator (CI). It ispossible to use the reserved bit rule to allow a receiver to feedback arate recommendation to transmitter side. A preferred embodiment can beto use the MSB to indicate a) switch rate if set to “1”, and b) retainthe current rate if set to “0” or vice versa. In this embodiment, thereceiver can make “fast recommendation or feedback” via the reserved RIbit. The receiver recommends to switch to a different rate than thepreviously transmitted PDU or to retain the same rate subject toadaptation rules and the link condition. Note that the transmitter canalways change rate on its own by setting the LSB of the RI filed. Inanother alternative embodiment, the MSB of the RI is used to indicate a)to increase TX power if set to “1”, and b) to decrease TX power if setto “0” or vice versa. As a result, the receiver can make recommendationon data rate as well as TX power adjustment.

FIG. 7 is flow chart of a method of rate indication for link adaptationfrom transmitter perspective in accordance with a novel aspect. In step701, a transmitting device indicates and adapts a data rate associatedwith a data packet to be transmitted to a receiving device in a wirelesscommunication network. The data packet comprises a preamble, a firstpacket portion, and a second packet portion. In step 702, thetransmitting device encodes the first packet portion in accordance witha first rate. The first packet portion comprises a rate indicationfield. In step 703, the transmitting device encodes the second packetportion in accordance with a second rate. The second rate is indicatedbased on a value of the rate indication field. In step 704, thetransmitting device transmits the data packet to the receiving device inthe wireless communication network. In one example, the transmittingdevice raises the second rate when detecting the link quality is good.In another example, the transmitting device lowers the second rate whendetecting the link quality is poor.

FIG. 8 is a flow chart of a method of rate indication for linkadaptation from receiver perspective in accordance with a novel aspect.In step 801, a receiving device receives a data packet from atransmitting device in a wireless communication network. The data packetcomprises a preamble, a first packet portion, and a second packetportion. In step 802, the receiving device decodes the first packetportion in accordance with a first rate. The first packet portioncomprises a rate indication field. In step 803, the receiving devicedecodes the second packet portion in accordance with a second rate. Thesecond rate is indicated based on a value of the rate indication field.In one example, the receiving device provides feedback information tothe transmitting device via an LMP message. In another example, thereceiving device provides recommended information to the transmittingdevice via a rate indication field for fast feedback. The recommendedinformation comprises a recommended rate or a transmit power adjustment.

Bluetooth Long Range Data Rates

A Bluetooth long-range channel SNR varies significantly, with largestandard deviation of SNRs in 37 channels. To cover SNR variation ofover +/−5 dB, it is desirable to have more data rates. Bluetooth longrange should also support a variety of applications with different datarate requirements. There is little additional hardware required tosupport the multiple data rates. Even for low data rate applications,they can benefit from higher data rates, shorter connection time, lowerpower consumption, and more robust link. For example, a Fitness Sensormay have a buffer of ˜2 kbytes of data, and an Ambulatory BiometricMonitor may have a buffer of ˜4.8 kbytes of data. Furthermore, Bluetoothlong range should also support mobility. When a device mobility is inmid-range, it should be able to operate at higher data rate for fastertransaction and reduced power. Providing a single data rate of 125 kbpsmight be too slow for some applications. Therefore, a rate adaptationmethod is proposed to support multiple data rates in Bluetoothlong-range networks.

FIG. 9 illustrates different modulation and coding scheme (MCS) optionsfor Bluetooth long range. For traditional Bluetooth Low Energy (LE), thephysical data rate is 1000 Kbps with no FEC coding and no patternmapping. For Bluetooth Long Range 125 mode (LR-125), the physical datarate is 125 Kbps with 1/2 FEC K=4 coding rate and 1:4 pattern mapping.For Bluetooth Long Range 250a mode (LR-250a), the physical data rate is250 Kbps with no FEC coding and 1:4 pattern mapping. For Bluetooth LongRange 250b mode (LR-250b), the physical data rate is 250 Kbps with 1/2FEC K=4 coding rate and 1:2 pattern mapping. For Bluetooth Long Range500a mode (LR-500a), the physical data rate is 500 Kbps with no FECcoding and 1:2 pattern mapping. For Bluetooth Long Range 500b mode(LR-500b), the physical data rate is 500 Kbps with 1/2 FEC K=4 codingrate and 1:1 pattern mapping. A transmitter thus can use different MCSoptions to support variable data rates by adapting to channelconditions, and then uses the novel rate indication field to indicatethe data rate to a receiver dynamically. As a result, for Bluetooth LongRange wireless networks with significantly varying channelconditions/SNRs, fast link adaptation can be achieved for differentapplications with different rate requirements, to provide higher datarate, reduce connection time, lower power consumption, and improve linkquality.

FIG. 10 is a simplified block diagram of a transmitter for supportingvariable data rates for Bluetooth long range. The transmitter comprisesa convolutional forward error correction (FEC) encoder 1010, a patternmapper 1020, and a modulation circuit 1030. The convolutional ForwardError Correction (FEC) encoder 1010 uses a non-systematic, non-recursiverate 1/2 code with constraint length K=4. A spreading factor P=4 meansthat the coded bits from the convolutional FEC encoder are mapped into aknown sequence by the Inner Pattern Mapper as follows: Coded bit 0 ismapped into sequence 1100 b, where the LSB (‘0’) is transmitted first;Coded bit 1 is mapped into sequence 0011 b, where the LSB (‘1’) istransmitted first. A spreading factor P=1 means that the coded bits fromthe convolutional FEC encoder 1010 are simply passed through the mapper.

For mode LR-125, the packet data rate is 125 Kbps, which is first codedby FEC encoder 1010 with 1/2 FEC K=4 coding rate, and then spread by theinner pattern mapper 1020 with P=4 (1:4), and finally modulated bymodulator 1030. For mode LR-250a, the packet data rate is 250 Kbps,which is not FEC encoded, and then spread by the inner pattern mapper1020 with P=4 (1:4), and finally modulated by modulator 1030. For modeLR-250b, the packet data rate is 250 Kbps, which is first coded by FECencoder 1010 with 1/2 FEC K=4 coding rate, and then spread by the innerpattern mapper 1020 with P=2 (1:2), and finally modulated by modulator1030. For mode LR-500a, the packet data rate is 500 Kbps, which is notFEC encoded, and then spread by the inner pattern mapper 1020 with P=2(1:2), and finally modulated by modulator 1030. For mode LR-500b, thepacket data rate is 500 Kbps, which is first coded by FEC encoder 1010with 1/2 FEC K=4 coding rate, and then passed through the inner patternmapper 1020 with P=1, and finally modulated by modulator 1030.

FIG. 11 is a flow chart of a method of supporting variable data ratesfrom transmitter perspective in accordance with one novel aspect. Instep 1101, a wireless transmitting device indicates and adapts a datarate associated with a data packet to a receiving device in a BluetoothLong Range wireless network. The data packet comprises a preamble, afirst packet portion, and a second packet portion. In step 1102, thetransmitting device encodes the first packet portion using a firstmodulation and coding scheme (MCS) in accordance with a first data rate.The first packet portion comprises a rate indication field. In step1103, the transmitting device encodes the second packet portion usingmodulation and coding scheme in accordance with a second data rate basedon a value of the rate indication field. In step 1104, the transmittingdevice transmits the data packet to the receiving device in the wirelessnetwork. In one example, the first data rate is 125 Kbps withconvolutional forward error correction and one to four pattern mapping,and the second data rate is 500 Kbps with convolutional forward errorcorrection and no pattern mapping.

FIG. 12 is a flow chart of a method of supporting variable data ratesfrom receiver perspective in accordance with one novel aspect. In step1201, a wireless receiving device receives a data packet transmittedfrom a transmitting device in a Bluetooth Long Range wireless network.The data packet comprises a preamble, a first packet portion, and asecond packet portion. In step 1202, the receiving device decodes thefirst packet portion in accordance with a first modulation and codingscheme corresponding to a first data rate. The first packet portioncomprises a rate indication field. In step 1203, the receiving devicedecodes the second packet portion in accordance with a second modulationand coding scheme corresponding to a second data rate based on a valueof the rate indication field. In one example, the first data rate is 125Kbps with convolutional forward error correction and one to four patternmapping, and the second data rate is 500 Kbps with convolutional forwarderror correction and no pattern mapping.

Although the present invention has been described in connection withcertain specific embodiments for instructional purposes, the presentinvention is not limited thereto. Accordingly, various modifications,adaptations, and combinations of various features of the describedembodiments can be practiced without departing from the scope of theinvention as set forth in the claims.

What is claimed is:
 1. A method comprising: indicating and adapting adata rate associated with a data packet to be transmitted from atransmitting device to a receiving device in a Bluetooth long-rangewireless network, wherein the data packet comprises a preamble, a firstpacket portion, and a second packet portion; encoding the first packetportion using a first modulation and coding scheme (MCS) in accordancewith a first data rate, wherein the first packet portion comprises arate indication field; encoding the second packet portion using a secondmodulation and coding scheme (MCS) in accordance with a second data ratebased on a value of the rate indication field; and transmitting the datapacket to the receiving device in the wireless network.
 2. The method ofclaim 1, wherein the first data rate is 125 Kbps with convolutionalforward error correction and one to four pattern mapping.
 3. The methodof claim 1, wherein the second data rate is 500 Kbps with convolutionalforward error correction and no pattern mapping.
 4. The method of claim1, wherein the second data rate is 250 Kbps with no convolutionalforward error correction and one to four pattern mapping.
 5. The methodof claim 1, wherein the transmitting device decides and transmits thedata packet at the data rate based on pre-determined rules.
 6. Themethod of claim 1, where transmitting device decides the data rateunilaterally without negotiating with the receiving device and withoutwaiting for a timeout of data transmission.
 7. The method of claim 1,further comprising: receiving feedback information carried by a linkmanagement protocol (LMP) message from the receiving device and therebydetermining the data rate.
 8. The method of claim 1, further comprising:receiving recommended information from the receiving device through arate indication field, wherein the recommended information comprises arecommended data rate or a transmit power adjustment.
 9. A wirelessdevice comprising: a rate indication circuit that is configured toindicate and adapt a data rate associated with a data packet to betransmitted to a receiving device in a Bluetooth long-range wirelessnetwork, wherein the data packet comprises a preamble, a first packetportion, and a second packet portion; an encoder that encodes the firstpacket portion using a first modulation and coding scheme (MCS) inaccordance with a first data rate, wherein the first packet portioncomprises a rate indication field, wherein the encoder also encodes thesecond packet portion using a second modulation and coding scheme (MCS)in accordance with a second rate based on a value of the rate indicationfield; and an RF transmitter that transmits the data packet to thereceiving device in the wireless network.
 10. The device of claim 9,wherein the first data rate is 125 Kbps with convolutional forward errorcorrection and one to four pattern mapping.
 11. The device of claim 9,wherein the second data rate is 500 Kbps with convolutional forwarderror correction and no pattern mapping.
 12. The device of claim 9,wherein the device decides and transmits the data packet at the datarate based on pre-determined rules.
 13. The device of claim 9, wheredevice decides the data rate unilaterally without negotiating with thereceiving device and without waiting for a timeout of data transmission.14. The device of claim 9, wherein the device receives feedbackinformation carried by a link management protocol (LMP) message from thereceiving device and thereby determining the data rate.
 15. The deviceof claim 9, wherein the device receives recommended information from thereceiving device through a rate indication field, and wherein therecommended information comprises a recommended data rate or a transmitpower adjustment.
 16. A method comprising: receiving a data packet froma transmitting device by a receiving device in a Bluetooth long-rangewireless network, wherein the data packet comprises a preamble, a firstpacket portion, and a second packet portion; decoding the first packetportion in accordance with a first modulation and coding scheme (MCS)corresponding to a first data rate, wherein the first packet portioncomprises a rate indication field; and decoding the second packetportion in accordance with a second modulation and coding scheme (MCS)corresponding to a second data rate based on a value of the rateindication field.
 17. The method of claim 16, wherein the first datarate is 125 Kbps with convolutional forward error correction and one tofour pattern mapping.
 18. The method of claim 16, wherein the seconddata rate is 500 Kbps with convolutional forward error correction and nopattern mapping.
 19. The method of claim 16, wherein the second datarate is 250 Kbps with no convolutional forward error correction and oneto four pattern mapping.
 20. The method of claim 16, wherein thereceiver automatically detects the second data rate of the data packetfrom the rate indication field.
 21. The method of claim 16, furthercomprising: transmitting feedback information carried by a linkmanagement protocol (LMP) message to the transmitting device.
 22. Themethod of claim 16, further comprising: transmitting recommendedinformation through a rate indication field to the transmitting device,wherein the recommended information comprises a recommended data rate ora transmit power adjustment.